1. Field of the Invention
The present invention relates to communication systems, and more particularly to an infrastructure for interactive television applications.
2. Description of the Related Art
FIGS. 1A and 1B illustrate a typical satellite based broadcast systems of the related art.
FIG. 1A shows television broadcasting system 20, which transmits and receives audio, video, and data signals via satellite. Although the present invention is described in the context of a satellite-based television broadcasting system, the techniques described herein are equally applicable to other methods of program content delivery, such as terrestrial over-the-air systems, cable-based systems, and the Internet. Further, while the present invention will be described primarily with respect to television content (i.e. audio and video content), the present invention can be practiced with a wide variety of program content material, including television content, audio content, or data content.
Television broadcasting system 20 includes transmission station 26, uplink dish 30, satellite 32, and receiver stations 34A-34C (collectively referred to as receiver stations 34). Transmission station 26 includes a plurality of input lines 22 for receiving various signals, such as analog television signals, digital television signals, video tape signals, original programming signals and computer generated signals containing HTML content. Additionally, input lines 22 receive signals from digital video servers having hard discs or other digital storage media. Transmission station 26 also includes a plurality of schedule feeds 24, which provide electronic schedule information about the timing and content of various television channels, such as that found in television schedules contained in newspapers and television guides. Transmission station 26 converts the data from schedule feeds 24 into program guide data. Program guide data may also be manually entered at the site of transmission station 26. The program guide data consists of a plurality of “objects”. The program guide data objects include data for constructing an electronic program guide that is ultimately displayed on a user's television.
Transmission station 26 receives and processes the various input signals received on input lines 22 and schedule feeds 24, converts the received signals into a standard form, combines the standard signals into a single output data stream 28, and continuously sends output data stream 28 to uplink dish 30. Output data stream 28 is a digital data stream that is compressed using MPEG2 encoding, although other compression schemes may be used.
The digital data in output data stream 28 are divided into a plurality of packets, with each such packet marked with a service channel identification (SCID) number. The SCIDs are later used by receiver 64 (shown in FIG. 1B) to identify the packets that correspond to each television channel. Error correction data is also included in output data stream 28.
Output data stream 28 is a multiplexed signal that is modulated by transmission station 26 using standard frequency and polarization modulation techniques. Output data stream 28 preferably includes 16 frequency bands, with each frequency band being either left polarized or right polarized. Alternatively, vertical and horizontal polarizations may be used.
Uplink dish 30 continuously receives output data stream 28 from transmission station 26, amplifies the received signal and transmits the signal to satellite 32. Although a single uplink dish and satellite are shown in FIG. 1, multiple dishes and satellites are preferably used to provide additional bandwidth, and to help ensure continuous delivery of signals.
Satellites 32 revolve in geosynchronous orbit about the earth. Satellites 32 each include a plurality of transponders that receive signals transmitted by uplink dish 30, amplify the received signals, frequency shift the received signals to lower frequency bands, and then transmit the amplified, frequency shifted signals back to receiver stations 34.
Receiver stations 34 receive and process the signals transmitted by satellites 32. Receiver stations 34 are described in further detail below with respect to FIG. 1B.
FIG. 1B is a block diagram of one of receiver stations 34, which receives and decodes audio, video and data signals. Receiver station 34 includes receiver dish 60, alternate content source 62, receiver 64, television 66, recording device 68, remote control 86 and access card 88. Receiver 64 includes tuner 70/demodulator/Forward Error Correction (FEC) decoder 71, digital-to-analog (D/A) converter 72, CPU 74, clock 76, memory 78, logic circuit 80, interface 82, infrared (IR) receiver 84 and access card interface 90. Receiver dish 60 receives signals sent by satellite 32, amplifies the signals and passes the signals on to tuner 70. Tuner 70 operates under control of CPU 74.
The CPU 74 operates under control of an operating system stored in the memory 78 or within an auxiliary memory within the CPU 74. The functions performed by CPU 74 are controlled by one or more control programs or applications stored in memory 78. Operating system and applications are comprised of instructions which, when read and executed by the CPU 74, cause the receiver 64 to perform the functions and steps necessary to implement and/or use the present invention, typically, by accessing and manipulating data stored in the memory 78. Instructions implementing such applications are tangibly embodied in a computer-readable medium, such as the memory 78 or the access card 88. The CPU 74 may also communicate with other devices through interface 82 or the receiver dish 60 to accept commands or instructions to be stored in the memory 78, thereby making a computer program product or article of manufacture according to the invention. As such, the terms “article of manufacture,” “program storage device” and “computer program product” as used herein are intended to encompass any application accessible by the CPU 74 from any computer readable device or media.
Memory 78 and access card 88 store a variety of parameters for receiver 64, such as a list of channels or services that the receiver 64 is authorized to process and generate displays for; the zip code and area code for the area in which receiver 64 is used; the model name or number of receiver 64; a serial number of receiver 64; a serial number of access card 88; the name, address and phone number of the owner of receiver 64; and the name of the manufacturer of receiver 64.
Access card 88 is removable from receiver 64 (as shown in FIG. 1B). When inserted into receiver 64, access card 88 is coupled to access card interface 90, which communicates via interface 82 to a customer service center (not pictured). Access card 88 receives access authorization information from the customer service center based on a user's particular account information. In addition, access card 88 and the customer service center communicate regarding billing and ordering of services.
Clock 76 provides the current local time to CPU 74. Interface 82 is preferably coupled to a telephone jack at the site of receiver station 34. Interface 82 allows receiver 64 to communicate with transmission station 26 via telephone lines. Interface 82 may also be used to transfer data to and from a network, such as the Internet.
The signals sent from receiver dish 60 to tuner 70 are a plurality of modulated rf signals. The desired rf signal is then downconverted to baseband by the tuner 70, which also generates in-phase and quadrature (I and Q) signals. These two signals are then passed to the demodulator/forward-error-correction (FEC) application specific integrated circuit (ASIC) 71. The demodulator 71 ASIC then demodulates the I and Q signals and the FEC decoder correctly identifies each transmitted symbol. The received symbols for quaternary phase shift keying (QPSK) or 8PSK signals carry two or three data bits, respectively. The corrected symbols are translated into data bits, which in turn are assembled in to payload data bytes, and ultimately into data packets. The data packets may carry 130 data bytes or 188 bytes (187 data bytes and 1 sync byte).
In addition to the digital satellite signals received by receiver dish 60, other sources of television content are also preferably used. For example, alternate content source 62 provides additional television content to television 66. Alternate content source 62 is coupled to tuner 70. Alternate content source 62 can be an antenna for receiving off the air signals NTSC signals, a cable for receiving ATSC signals, or other content source. Although only one alternate content source 62 is shown, multiple sources can be used.
Initially, as data enters receiver 64, tuner 70 looks for a boot object. Boot objects are always transmitted with the same SCID, so tuner 70 knows that it must look for packets marked with that SCID. A boot object identifies the SCIDs where all other program guide objects can be found. The information from the boot object is used by tuner 70 to identify packets of program guide data and route them to memory 78.
Remote control 86 emits infrared signals that are received by infrared (IR) receiver 84 in receiver 64. Other types of data entry devices may alternatively be used, such as an ultra-high frequency (UHF) remote control, a keypad on receiver 64, a remote keyboard and a remote mouse. When a user requests the display of a program guide by pressing the “guide” button on remote control 86, a guide request signal is received by IR receiver 84 (shown in FIG. 2) and transmitted to logic circuit 80. Logic circuit 80 informs CPU 74 of the guide request. In response to the guide request, CPU 74 causes memory 78 to transfer a program guide digital image to D/A converter 72. D/A converter 72 converts the program guide digital image into a standard analog television signal, which is then transmitted to television 66. Television 66 then displays the program guide. Television 66 may alternatively be a digital television, in which case no digital to analog conversion is necessary.
Users interact with the electronic program guide using remote control 86. Examples of user interactions include selecting a particular channel or requesting additional guide information. When a user selects a channel using remote control 86, IR receiver 84 relays the user's selection to logic circuit 80, which then passes the selection on to memory 78 where it is accessed by CPU 74. CPU 74 instructs tuner 70 to output the audio and video packets for the selected channel to D/A converter 72. D/A converter 72 performs an MPEG2 decoding step on received packets, converts the packets to analog signals, and outputs the analog signals to television 66.
Recently, broadcasting system 20 has begun transmitting interactive services and channels to receiver stations 34. This new layer of interactivity creates new challenges and issues to be resolved in system 20, such as how the interactive commands are sent and used within system 20. It can be seen, then, that there is a need in the art to allow for control and management of interactive services in a broadcasting system.